Say that 2 of the players are soldiers who have sworn to hold a particular pass; each one has an advantage of 'My men are at my side' reflecting the rest of the troops.

Another player is an enemy general, who is has the PStr 'Terrifying Leader' and there's an NPC commander trying to undermine him.

Now, say we've got a pretty nice map of the pass as a visual aid. The soldiers have a few scenes with a shaman from the mountains who doesn't want blood spilt here, but is rebuffed. In the course of that time the soldiers have clearly been setting up defenses and they do a good job at describing why they will have a terrain advantage when the enemy army arrives.

When the enemy army arrives, how do I make that preparation stuff relevant? Does it have to be irrelevant?

Purely "gaming system", if you can only have one PS adding dice in a conflict (as Vincent has said), then it makes some sense not to add new PS's that overlap in the stats they are used with or the situations they apply in.

So, increase the strength of a PS or add a PS good in different situations or with different stat dice (e.g., My Men at My Side doesn't help acting solo, for example, so add a PS for such actions, or affecting different stat dice). A player of a war-sorceress in a game I was in had one PS for sorceries good in battles and another PS for mucking about with people's minds in more social situations.

So make the preparations something good for using with different dice, if My Men are for "With Violence", then instead of fortifications make it secret pathways and tunnels they have created/found that are good with "Covertly".

Ryan: You don't have to wait for next chapter. You can create new particular strengths whenever. They're super-easy to create, on purpose.

Always, follow the logic of the particular strength in the fiction, applying the particular strength rules accordingly.

Except, roll only one particular strength's die in any given action sequence (your choice which). Bring both or any particular strengths into play in the fiction, as you like. The reason for this is, each additional die you roll reduces the value of the advantage die.

I like Rob's "make them good for different stats" suggestion quite a lot.

Now look, one more thing. The game text communicates what I consider to be crucial about how particular strengths work, and it's silent about most of what I consider to be unimportant about how particular strengths work. If the rules are silent on some point, presume that they'll comfortably accomodate you however you approach that point.

If you interpret them as super-strict (for example, the only time the rules mention creating new particular strengths is during chapter setup, so if you daren't create one midchapter), that's fine with me. You aren't playing wrong. They'll work great under those conditions, same as they'll work great if you interpret them as tools to use whenever and however you see fit.

Vincent; I'm going to re-state what I think you just said, to see if I actually get the concept:

Players or the GM can create particular strengths whenever they seem necessary, in the same way that the GM can stat up NPCs on the fly, when they seem necessary. A character can use a particular strength whenever the fiction makes it so (but only one particular strength die can be rolled by any one character in any one conflict), but a character can only write a particular strength on his sheet at the top of a chapter. Particular strengths, especially unique ones that are defined as 'items', can be passed around during a chapter, but do not get written on various character sheets during a chapter. You can negotiate for the loser of a conflict to mark a particular strength off his sheet, but you cannot negotiate for the winner to write one on his sheet.

Now, for some examples:

Ryan's troops build 'Massive Fortifications in Breakspine Pass', which are significance 1, are a d8, unique, usable with Directly (or Self-Protection for NPCs). No one currently has this particular strength on their character sheet, but whoever is defending Breakspine Pass in the fiction can use that die if they want it. At the top of a subsequent chapter, someone could write it on their character sheet if they want to. Even a new NPC might wind up with it on his sheet -- the newly-appointed commander of the defending army, perhaps.

My character, Balashi, who has a magic sword called 'Bloodletter', (sig 1, d8, unique, usable with Violence (or Action for NPCs)) is unwilling to assault the pass, but is willing to lend 'Bloodletter' to your character, Azan (in the treacherous hopes that you will lead the charge, and die sloppy :) ). Azan can use the sword while he has it (and Balashi can't) -- but upon Balashi's next chapter appearance, it's still on Balashi's sheet, and upon Azan's next chapter appearance, it's not on his. (This could also happen if Azan beat Balashi in a conflict, and we negotiated that he took the sword, but not that I marked it off Balashi's character sheet.)

In a later chapter, the oracle spits out the one about the 'warlord's head in a carved cask'. We generate characters, and 'the owner of the head' is of course on the list -- but for whatever reason, no one picks that character as a PC or NPC. We decide that it's the head of Azan, who did in fact die sloppy. The head is around in the fiction, so if it comes up, someone could stat up the head -- maybe as a talking oracular device that gives advice in battle (sig 1, d8, unique, usable for Myself (or Self-Protection for NPCs). No one has the head on his or her sheet, but anyone who acquires it in the fiction can use it. Balashi ends the chapter with the head in his possession, and in his next chapter appearance, I decide to write it on his sheet as a (semi)permanent improvement.

Well, those are the old "when it's written on your sheet vs when you just happen to have it" rules, which aren't in the book. "Follow the internal logic of each individual particular strength" replaces them. If you and your group thinks that your examples follow the individual particular strengths' internal logic, they're kosher. Otherwise, they aren't. They seem fine to me, but you can't be checking with me every time you make a particular strength.

As GM controlling NPC's or as other PC's I would also be looking at "picking up any loose PS" for use as being precisely one of those "oh no you don't" events that is disputed and leads to conflict. No gain without pain or at least risk of it. Despite there only being one PS to use at a time, having the flexibility of another tactic etc. seems an advantage.